bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulations of electric field gradient fluctuations and dynamics around sodium ions in ionic liquids
Authors: Gimbal-Zofka Yann , Karg Beatrice , Dziubinska-Kühn Katarzyna , Kowalska Magdalena , Wesolowski Tomasz A. , Rumble Christopher A. 
Published: December 2022

The T1 relaxation time measured in nuclear magnetic resonance experiments contains information about electric field gradient (EFG) fluctuations around a nucleus, but computer simulations are typically required to interpret the underlying dynamics. This study uses classical molecular dynamics (MD) simulations and quantum chemical calculations, to investigate EFG fluctuations around a Na+ ion dissolved in the ionic liquid 1-ethyl 3-methylimidazolium tetrafluoroborate, [Im21][BF4], to provide a framework for future interpretation of NMR experiments. Our calculations demonstrate that the Sternheimer approximation holds for Na+ in [Im21][BF4], and the anti-shielding coefficient is comparable to its value in water. EFG correlation functions, CEFG(t), calculated using quantum mechanical methods or from force field charges are roughly equivalent after 200 fs, supporting the use of classical MD for estimating T1 times of monatomic ions in this ionic liquid. The EFG dynamics are strongly bi-modal, with 75%–90% of the de-correlation attributable to inertial solvent motion and the remainder to a highly distributed diffusional processes. Integral relaxation times, ⟨τEFG⟩, were found to deviate from hydrodynamic predictions and were non-linearly coupled to solvent viscosity. Further investigation showed that Na+ is solvated by four tetrahedrally arranged [BF4]− anions and directly coordinated by ∼6 fluorine atoms. Exchange of [BF4]− anions is rare on the 25–50 ns timescale and suggests that motion of solvent-shell [BF4]− is the primary mechanism for the EFG fluctuations. Different couplings of [BF4]− translational and rotational diffusion to viscosity are shown to be the source of the non-hydrodynamic scaling of ⟨τEFG⟩.
Simulation and theoretical study of AlGaN-based deep-ultraviolet light-emitting diodes with a stepped electron barrier layer
Authors: Zhao Fengyi , Jia Wei , Dong Hailiang , Jia Zhigang , Li Tianbao , Yu Chunyan , Zhang Zhuxia , Xu Bingshe 
Published: December 2022

Owing to the COVID-19 outbreak, sterilization of deep-ultraviolet light-emitting diodes (DUV LEDs) has attracted increasing attention. Effectively improving the radiative recombination efficiency and mitigating the efficiency degradation, mainly caused by electron leakage and nonradiative recombination, have also emerged as two of the main issues to be addressed. In this study, a DUV LED epitaxial structure with a novel electron-blocking layer (EBL) is proposed. The DUV LED with a luminescence wavelength of ∼297 nm was formed by the stepwise variation of the Al component. Through the simulation and analysis of its performance parameters, we found that, compared to the conventional EBL structure, this new EBL structure not only reduces the electron leakage to the p-region effectively but also increases the hole injection into the active region, resulting in an increase in carrier concentration in the active region, a two-to-three-fold increase in the radiative recombination rate, and a 58% increase in the internal quantum efficiency, thus alleviating the efficiency droop and achieving a more efficient operation at high current densities.
Trabecular bone ontogeny tracks neural development and life history among humans and non-human primates
Authors: Saers Jaap P. P. , Gordon Adam D. , Ryan Timothy M. , Stock Jay T. 
Published: December 2022

Trabecular bone—the spongy bone inside marrow cavities—adapts to its mechanical environment during growth and development. Trabecular structure can therefore be interpreted as a functional record of locomotor behavior in extinct vertebrates. In this paper, we expand upon traditional links between form and function by situating ontogenetic trajectories of trabecular bone in four primate species into the broader developmental context of neural development, locomotor control, and ultimately life history. Our aim is to show that trabecular bone structure provides insights into ontogenetic variation in locomotor loading conditions as the product of interactions between increases in body mass and neuromuscular maturation. Our results demonstrate that age-related changes in trabecular bone volume fraction (BV/TV) are strongly and linearly associated with ontogenetic changes in locomotor kinetics. Age-related variation in locomotor kinetics and BV/TV is in turn strongly associated with brain and body size growth in all species. These results imply that age-related variation in BV/TV is a strong proxy for both locomotor kinetics and neuromuscular maturation. Finally, we show that distinct changes in the slope of age-related variation in bone volume fraction correspond to the age of the onset of locomotion and the age of locomotor maturity. Our findings compliment previous studies linking bone development to locomotor mechanics by providing a fundamental link to brain development and life history. This implies that trabecular structure of fossil subadults can be a proxy for the rate of neuromuscular maturation and major life history events like locomotor onset and the achievement of adult-like locomotor repertoires.
Alanine synthesized by alanine dehydrogenase enables ammonium-tolerant nitrogen fixation in
Paenibacillus sabinae
T27
Authors: Li Qin , Zhang Haowei , Song Yi , Wang Minyang , Hua Chongchong , Li Yashi , Chen Sanfeng , Dixon Ray , Li Jilun 
Published: December 2022

Most diazotrophs fix nitrogen only under nitrogen-limiting conditions, for example, in the presence of relatively low concentrations of NH
4
+
(0 to 2 mM). However,
Paenibacillus sabinae
T27 exhibits an unusual pattern of nitrogen regulation of nitrogen fixation, since although nitrogenase activities are high under nitrogen-limiting conditions (0 to 3 mM NH
4
+
) and are repressed under conditions of nitrogen sufficiency (4 to 30 mM NH
4
+
), nitrogenase activity is reestablished when very high levels of NH
4
+
(30 to 300 mM) are present in the medium. To further understand this pattern of nitrogen fixation regulation, we carried out transcriptome analyses of
P. sabinae
T27 in response to increasing ammonium concentrations. As anticipated, the
nif
genes were highly expressed, either in the absence of fixed nitrogen or in the presence of a high concentration of NH
4
+
(100 mM), but were subject to negative feedback regulation at an intermediate concentration of NH
4
+
(10 mM). Among the differentially expressed genes,
ald1
, encoding alanine dehydrogenase (ADH1), was highly expressed in the presence of a high level of NH
4
+
(100 mM). Mutation and complementation experiments revealed that
ald1
is required for nitrogen fixation at high ammonium concentrations. We demonstrate that alanine, synthesized by ADH1 from pyruvate and NH
4
+
, inhibits GS activity, leading to a low intracellular glutamine concentration that prevents feedback inhibition of GS and mimics nitrogen limitation, enabling activation of
nif
transcription by the nitrogen-responsive regulator GlnR in the presence of high levels of extracellular ammonium.
CCAUV.W-K2 final report - key comparison CCAUV.W-K2: calibration of hydrophones in the frequency range from 250 Hz to 500 kHz
Authors: Robinson S P , Harris P M , Ford B , Ablitt J , Yi Chen , Biber Alper , Corakci Ata Can , Costa-Felix Rodrigo , Crocker Steven , Isaev Alexander , Tyalimpi Vumile , Latha G 
Published: December 2022

Main text
This report is the final report for key comparison CCAUV.W-K2. This key comparison covers primary free-field standards for sound in water at frequencies between 250 Hz and 500 kHz. This project is one of the key comparisons organised under the auspices of the Consultative Committee on Acoustics, Ultrasound and Vibration (CCAUV) of the CIPM.
This report has the status of a Final Report and has been submitted to the Key Comparison Database (KCDB). In the report, the results of participants are presented with the Key Comparison Reference Values and Degrees of Equivalence. The results are calculated according to the procedures agreed after consideration of the Draft A1 and A2 reports, and the Draft B report has been approved by the CCAUV. All participants have had the opportunity to give final agreement on the contents and amendments have been made to account for their comments.
In many respects, the comparison has been a success with good agreement achieved over an extended lower frequency range compared to the previous CCAUV.W-K1 comparison, the lower frequency limit for CCAUV.W-K2 being extended down by two octaves to 250 Hz. The generally more difficult frequency range from 100 kHz to 500 kHz has also shown very good agreement between the participants. However, in the range 60 kHz to 100 kHz the agreement was not as good, with three participants exhibiting some discrepant results.
To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.
The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Classical and quantum bicosmology with noncommutativity
Authors: Kan Nahomi , Aoyama Takuma , Shiraishi Kiyoshi 
Published: December 2022

AbstractRecently, Falomir, Gamboa, Méndez, Gondolo and Maldonado proposed a bicosmology scenario for solving some cosmological problems related to inflation, dark matter, and thermal history of the Universe (Falomiret al(2017Phys. Rev.D96083534); Falomiret al(2018Phys. Lett.B785399); Falomiret al(2020Symmetry12435); Maldonado and Méndez (2021Phys. Rev.D103123505)) . Their plan is to introduce noncommutativity into the momentum space of the two scale factors. In the present paper, we revisit their model and first consider exact classical solutions in the model with constant noncommutativity between dynamical variables and between canonical momenta. We also hypothesize that the noncommutativity appears when the scale factors are small, and show the behavior of the classical solution in that case with momentum-space noncommutativity. Finally, we write down the Wheeler–DeWitt equation in that case and examine the behavior of the solution.
Energy equations for projectiles with linear and quadratic drag
Authors: Bradshaw John L 
Published: December 2022

Abstract
Although linear and quadratic drag are treated early in upper-level undergraduate mechanics courses, energy dissipation due to drag is not. In this paper, energy equations with exact analytic formulas for dissipation due to air resistance are developed for projectiles using linear and quadratic drag models, based on the work–energy theorem. Examples with analytic results for specific cases are presented for quadratic drag in one dimension, and linear drag in one and two dimensions suggested as student assignments. Similarly, three numerical examples of energy dissipation showing kinetic, potential, and/or dissipated energy versus either time or distance are presented, suggested as assignments that students could code and graph in a spreadsheet application.
Disconnected entanglement entropy as a marker of edge modes in a periodically driven Kitaev chain
Authors: Mondal Saikat , Sen Diptiman , Dutta Amit 
Published: December 2022

Abstract
We study the disconnected entanglement entropy (DEE) of a Kitaev chain in which the chemical potential is periodically modulated with δ-function pulses within the framework of Floquet theory. For this driving protocol, the DEE of a sufficiently large system with open boundary conditions turns out to be integer-quantized, with the integer being equal to the number of Majorana edge modes localized at each edge of the chain generated by the periodic driving, thereby establishing the DEE as a marker for detecting Floquet Majorana edge modes. Analyzing the DEE, we further show that these Majorana edge modes are robust against weak spatial disorder and temporal noise. Interestingly, we find that the DEE may, in some cases, also detect the anomalous edge modes which can be generated by periodic driving of the nearest-neighbor hopping, even though such modes have no topological significance and not robust against spatial disorder. We also probe the behavior of the DEE for a kicked Ising chain in the presence of an integrability breaking interaction which has been experimentally realized.
Prediction of erbium–nitrogen compounds as high-performance high-energy-density materials
Authors: Cai Huapeng , Wang Xin , Zheng Yueshao , Jiang Xing-xing , Zeng Jiang , Feng Yexin , Chen Keqiu 
Published: December 2022

Abstract
To explore high-energy-density materials, intense attention has been focused on how to stabilize the N–N bond in nitrogen-rich compounds. Here, we report several stable phases of erbium–nitrogen compounds ErN
x
as high-energy-density materials. Specifically, the phase diagrams of stable high-pressure structures Immm-ErN2, C2-ErN3, P

1
ˉ

-ErN4, and P

1
ˉ

-ErN6, are theoretically studied by combining first-principles calculation with particle swarm optimization algorithm. In these erbium–nitrogen compounds, the N–N bonds are stabilized as diatomic quasi-molecule N2, helical-like nitrogen chains, armchair nitrogen chains, and armchair–anti-armchair nitrogen chains, respectively. Among them, the P

1
ˉ

-ErN6 harbors excellent stability at high thermal up to 1000 K. More importantly, the P

1
ˉ

-ErN6 has outstanding explosive performance with high-energy-density of 1.30 kJ g−1, detonation velocity of 10.87 km s−1, and detonation pressure of 812.98 kbar, which shows its promising application prospect as high-energy-density materials.
Hierarchical dispersion Lempel–Ziv complexity for fault diagnosis of rolling bearing
Authors: Li Yongjian , Tan Li , Xiao Meng , Xiong Qing 
Published: December 2022

Abstract
The fault information of rolling bearings is generally contained in vibration signals. How to efficiently unearth fault information from the raw signals is the key to detecting and evaluating the health condition of mechanical equipment. Therefore, a hierarchical dispersion Lempel–Ziv complexity (HDLZC) feature extraction method is developed in this paper to improve the accuracy of fault diagnosis. In this method, dispersion theory addresses the deficiency of Lempel–Ziv complexity, and can obtain more fault features from the raw signal. Second, the hierarchical extraction of high- and low-frequency components from time series can improve the ability to describe dynamic features. Simulations and experiments respectively demonstrate the predominance of HDLZC. The experimental results reveal that this method is significantly better than multiscale dispersive Lempel–Ziv complexity, hierarchical Lempel–Ziv complexity, multiscale dispersion entropy, and multiscale permutation entropy in extracting fault information.
Fault identification method of micro turbine blade based on the order spectral entropy of bearing vibration
Authors: Li Ning , Zhang Jingqi , Zhai Jingyu , Han Qingkai 
Published: December 2022

Abstract
In view of the difficulty in identifying the state of the micro turbine blade, this paper uses the order spectral entropy analysis method to extract the characteristic information of the blade fault based on the measured micro turbine bearing vibration data. Firstly, a micro-turbine test bench was established. The normal temperature stable inlet flow was produced by a blower, the high temperature and pressure unstable airflow was generated by turbojet combustion chamber, and the working inlet mode of a micro-turbine with a wide range of speed changes was simulated. The vibration signal of the bearing was collected by shell drilling, a variety of time-frequency domain feature analysis methods based on vibration signal are difficult to effectively identify blade faults under the combined action of unstable airflow and frequent variable speed. In this paper, the bearing vibration data in time domain is converted to the vibration data in angle domain, and then the order amplitude and entropy were compared and analyzed. The results show that the proposed method can effectively identify the blade fracture and fouling faults under the driving of stable and unstable airflow in the speed range of 0–20 000 r min−1. This method provides a new method for micro turbine blade condition monitoring through bearing vibration data.
Isomerism effects in relaxation dynamics of Au24(SR)16 thiolate-protected gold nanoclusters
Authors: Sun Yuanze , Yu Xueke , Liu Pengye , Han Wenhua , Xu Wen-wu , Su Yan , Zhao Jijun 
Published: December 2022

Abstract
Understanding the excited state behavior of isomeric structures of thiolate-protected gold nanoclusters is still a challenging task. In this paper, based on grand unified model and ring model for describing thiolate-protected gold nanoclusters, we have predicted four isomers of Au24(SR)16 nanoclusters. Density functional theory calculations show that the total energy of one of the predicted isomers is 0.1 eV lower in energy than previously crystallized isomer. The nonradiative relaxation dynamics simulations of Au24(SH)16 isomers are performed to reveal the effects of structural isomerism on relaxation process of the lowest energy states, in which that most of the low-excited states consist of core states. In addition, crystallized isomer possesses the shorter e–h recombination time, whereas the most stable isomer has the longer recombination time, which may be attributed to the synergistic effect of nonadiabatic coupling and decoherence time. Our results could provide practical guidance to predict new gold nanoclusters for future experimental synthesis, and stimulate the exploration of atomic structures of same sized gold nanoclusters for photovoltaic and optoelectronic devices.
Enhanced photonic spin Hall effect in Dirac semimetal metamaterial enabled by zero effective permittivity
Authors: Da Haixia , Song Qi , Hu Pengya , Ye Huapeng 
Published: December 2022

Abstract
With the recent discovery of three dimensional Dirac semimetals, their integrations with the optoelectronic devices allow the novel optical effects and functionalities. Here, we theoretically report the photonic spin Hall effect in a periodic structure, where three dimensional Dirac semimetals and the dielectric materials are assembled into the stack. The incident angle and frequency dependent spin shift spectrum reveals that the spin shifts of the transmitted wave in this structure emerge the obvious peaks and valleys for the horizontal polarized wave and their magnitudes and positions display a distinct dependence on the incident angle around the specific frequency. These observations originate from its zero value of the effective perpendicular permittivity and its greatly reduced transmission in the multilayered structure, whose mechanism is different from those in the previous works. Moreover, both the peaks and valleys of the transmitted spin shift are significantly sensitive to the Fermi energy of three dimensional Dirac semimetals, whose magnitudes and positions can be tuned by varying it. Our results highlight the vital role of three dimensional Dirac semimetals in their applications of the spin photonic devices and pave the way to explore the tunable photonic spin Hall effect by engineering their Fermi energies.
NuTracker: a coordinate-based neural network representation of lung motion for intrafraction tumor tracking with various surrogates in radiotherapy
Authors: Liu Cong , Wang Qingxin , Si Wen , Ni Xinye 
Published: December 2022

Abstract

Objective. Tracking tumors and surrounding tissues in real-time is critical for reducing errors and uncertainties during radiotherapy. Existing methods are either limited by the linear representation or scale poorly with the volume resolution. To address both issues, we propose a novel coordinate-based neural network representation of lung motion to predict the instantaneous 3D volume at arbitrary spatial resolution from various surrogates: patient surface, fiducial marker, and single kV projection. Approach. The proposed model, namely NuTracker, decomposes the 4DCT into a template volume and dense displacement fields (DDFs), and uses two coordinate neural networks to predict them from spatial coordinates and surrogate states. The predicted template is spatially warped with the predicted DDF to produce the deformed volume for a given surrogate state. The nonlinear coordinate networks enable representing complex motion at infinite resolution. The decomposition allows imposing different regularizations on the spatial and temporal domains. The meta-learning and multi-task learning are used to train NuTracker across patients and tasks, so that commonalities and differences can be exploited. NuTracker was evaluated on seven patients implanted with markers using a leave-one-phase-out procedure. Main results. The 3D marker localization error is 0.66 mm on average and <1 mm at 95th-percentile, which is about 26% and 32% improvement over the predominant linear methods. The tumor coverage and image quality are improved by 5.7% and 11% in terms of dice and PSNR. The difference in the localization error for different surrogates is small and is not statistically significant. Cross-population learning and multi-task learning contribute to performance. The model tolerates surrogate drift to a certain extent. Significance. NuTracker can provide accurate estimation for entire tumor volume based on various surrogates at infinite resolution. It is of great potential to apply the coordinate network to other imaging modalities, e.g. 4DCBCT and other tasks, e.g. 4D dose calculation.
Charge-plasma based symmetrical-gate complementary electron–hole bilayer TFET with improved performance for sub-0.5 V operation
Authors: Anam Aadil , Kumar Naveen , Amin S Intekhab , Prasad Dinesh , Anand Sunny 
Published: December 2022

Abstract
In this paper, the complementary charge-plasma (CP) based symmetrical-gate electron–hole bilayer (EHB) tunnel field-effect transistor (TFET) at a low operating voltage (⩽0.5 V) is introduced. Where, by using CP technique, the source/drain and EHB-channel is induced by depositing metal electrode with appropriate work function. Moreover, the immunity against random dopant fluctuations and the feasibility of a self-aligned process due to a symmetrical top/bottom gate arrangement without the need for a high thermal annealing process make the fabrication of the proposed EHB-TFET very reliable and efficient. Moreover, by implementing the density gradient quantum correction model, the quantum confinement and its effect on confining the 2D electron–hole concentration are also corrected as the proposed device has a smaller channel thickness of 5 nm. The proposed device shows superior performance against almost all Si-based CP-TFETs with a higher ON-current of 47.33 μA μm−1, a smaller average subthreshold swing of 13.53 mV dec−1 and a high ON-current to OFF-current ratio of 2.16 × 1013. This indicates that the proposed device is a promising candidate for future low-power applications.