bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum droplets in three-dimensional Bose–Einstein condensates
Authors: Otajonov Sherzod R 
Published: April 2022

Abstract
The properties of 3D Bose–Einstein condensate have been studied with variational and numerical methods. In the variational approach, we use the super-Gaussian trial function, and it is demonstrated that this trial function is a good approach for providing the descriptions of the quantum droplets. The analytical equations for the variational parameters are obtained. The frequency of small oscillations of quantum droplets near the equilibrium position is estimated. It is also found that periodic modulation of the coupling constants leads to resonance oscillations of the quantum droplets parameters or emission of waves depending on the amplitude of the modulations. The predictions are supported by direct numerical simulation of the governing equation.
About the possibility for using graphene layers 12
C–13
C for quantum computation
Authors: López Gustavo V , Vizcaíno G Jorge O 
Published: April 2022

Abstract
We used a graphene 12
C matrix doped with 13
C atoms in a squared and center-triangular configuration, where only the interaction 13
C–13
C with their magnetic moments are considered. This is done in the presence of a constant magnetic field parallel to the layers and a transverse rf-magnetic field in order to simulate the NOT gate (single layer), controlled-not quantum gate (two layers), and controlled-controlled-not quantum gate (three layers). However, as it would be explained in more detail throughout this article, a single qubit rotation defined by a single graphene layer was not possible to construct. We found that frequencies needed to perform this transitions do not depend on the number of 13
C atoms on each layer, which means that we can make transitions between two distant states with big separation of energy levels (m and n states) with lower frequency pulses

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Competitive protein adsorption on charge regulating silica-like surfaces: the role of protonation equilibrium
Authors: Cathcarth Marilina , Picco Agustin S , Mondo Gabriela B , Cardoso Mateus B , Longo Gabriel S 
Published: April 2022

Abstract
We develop a molecular thermodynamic theory to study the interaction of some proteins with a charge regulating silica-like surface under a wide range of conditions, including pH, salt concentration and protein concentration. Proteins are modeled using their three dimensional structure from crystallographic data and the average experimental pKa of amino acid residues. As model systems, we study single-protein and binary solutions of cytochrome c, green fluorescent protein, lysozyme and myoglobin. Our results show that protonation equilibrium plays a critical role in the interactions of proteins with these type of surfaces. The terminal hydroxyl groups on the surface display considerable extent of charge regulation; protein residues with titratable side chains increase protonation according to changes in the local environment and the drop in pH near the surface. This behavior defines protein–surface interactions and leads to the emergence of several phenomena: (i) a complex non-ideal surface charge behavior; (ii) a non-monotonic adsorption of proteins as a function of pH; and (iii) the presence of two spatial regions, a protein-rich and a protein-depleted layer, that occur simultaneously at different distances from the surface when pH is slightly above the isoelectric point of the protein. In binary mixtures, protein adsorption and surface–protein interactions cannot be predicted from single-protein solution considerations.
3D roughness standard for performance verification of topography instruments for additively-manufactured surface inspection
Authors: Jones Christopher W , Sun Wenjuan , Boulter Hal , Brown Stephen 
Published: April 2022

Abstract
The unique complex topography of additively-manufactured surfaces—and the recent rapid evolution of instruments and techniques to measure them—limits trust in inspection data, in direct conflict with the requirements of application areas such as aerospace, where failure of a part can have serious safety consequences. Topography instrument manufacturers and end-users require measurement standards with a controlled reproduction of representative additively-manufactured surfaces to calibrate, performance-verify and intercompare instruments for inspection tasks, thereby improving confidence in measurement. The design of such a surface texture measurement standard is reported, optimised for optical areal topography-measuring instruments and compatible with x-ray computed tomography instruments. Machined from an additively-manufactured blank, the standard’s four sides represent increasing levels of post-processing from the as-deposited surface. Datum features on the measurement standard facilitate direct comparison between topography instruments. Integrated step features support the calibration of an instrument’s Z scale. Calibration of a prototype of the standard is reported; the prototype is matched to a typical aerospace Scalmalloy™ additive manufacturing process. The calibration is also a trial application of a large-area chromatic confocal microscope; this instrument appears capable of calibrating relatively rough measurement standards if required to do so. Reference Ra and S-parameter measurements and associated measurement uncertainties are presented, correlation between parameters noted, and choice and consequences of filter settings discussed.
A smoothly tunable shape memory metamaterial with adaptive bandgaps for ultra-wide frequency spectrum vibration control
Authors: Song Yihao , Shen Yanfeng 
Published: April 2022

Abstract
This article presents a smoothly tunable shape memory elastic metamaterial with adaptive bandgaps enabling the broadband frequency vibration control. The underlying bandgap-tuning mechanism arises from the reversible large deformation induced by shape memory alloy (SMA) element under electro-thermal loads, through which, various microstructural shape morphing could be achieved. Via delicately designing the unit cell, the numerically obtained band structures and effective medium properties display a successful attainment of the vibration stop-passing band formation and smoothly controllable two-way tuning phenomenon for a series of transitional and intermediate status. The overall controllable frequency scope could be shifted over an ultra-wide band. Subsequently, a systematic parametric study is carried out to unfold the bandgap-adjusting patterns by altering the apparent structural stiffness and the SMA elastic modulus, individually. The finite element harmonic analysis of a metamaterial unit-cell-chain model is further investigated to verify the effectiveness of vibration suppression and the variability of the stopband region from the frequency spectra and the equivalent stresses images. Finally, the experimental demonstration is performed to validate the numerical predication from a practical perspective. The proposed design may possess enabling application potentials for future active vibration control and noise isolation in engineering facilities.
Triple-vortex bremsstrahlung
Authors: Wang W Q , Lei S H , Geng X S , Shen B F , Bu Z G , Ji L L 
Published: April 2022

Abstract
Particles in vortex states have gained arising interests due to the additional degree of freedom—the orbital angular momentum (OAM) inherently existing in the state. With the increasing energy of vortex particles (photons, leptons etc), the research has gradually transitioned from the classical field regime to collisions of vortex particles in the quantum-field regime. The latter provides a new way to study the rich properties of particle physics. Here, we show the characteristics of vortex states in bremsstrahlung by deriving the corresponding scattering probability following the quantum-electrodynamics theory. The theory allows us to obtain the OAM distribution of the outgoing vortex photon and the law of OAM transfer during interaction. It is shown that the generated photon takes most of the initial electron OAM, especially when the latter is more energetic. The opening angle of outgoing particles in vortex bremsstrahlung is also significantly different from plane wave scattering. The effects of polarization and non-zero impact parameter are also discussed. The results illustrate the unique feature of vortex scattering and suggest a feasible way to generate high-energy vortex photons—a novel source in studying nuclear physics.
Measuring and adjusting the distance between the center of mass and optical center of a free-falling body in an absolute gravimeter
Authors: Ye Yu , Xiang Hu , Wen-jing Shi , Zi-wei Ye , Kang Lü , Fu Bao , Ruo-lin Wang , Jin-yang Feng 
Published: April 2022

Abstract
In an absolute gravimeter based on optical interferometry, the rotation of a falling body leads to inaccurate gravity measurement. By arranging the center of mass (COM) of the falling body together with its optical center (OC), the rotation error can be minimized rapidly. An optical measurement system with a two-stage pendulum structure is proposed to measure the distance between the COM and the OC of the falling body. The displacement of the OC is measured by an orthogonal interferometer while the falling body twists around the torsion wire, and the rotation angle of the falling body is measured synchronously by a photoelectric autocollimator. It is proved that a twist of the falling body by 2.4 degrees leads to a significant offset of about 0.2 nm along the direction of the laser beam. This results in a limit error of the measurement of the distance between the OC and the COM less than 1 μm. Thus, the rotation error in absolute gravity measurement is reduced to 0.07 μGal.
Analytic beamformer transformation for transfer learning in motion-onset visual evoked potential decoding
Authors: Libert Arno , Van Den Kerchove Arne , Wittevrongel Benjamin , Van Hulle Marc M 
Published: April 2022

Abstract

Objective. While decoders of electroencephalography-based event-related potentials (ERPs) are routinely tailored to the individual user to maximize performance, developing them on populations for individual usage has proven much more challenging. We propose the analytic beamformer transformation (ABT) to extract phase and/or magnitude information from spatiotemporal ERPs in response to motion-onset stimulation. Approach. We have tested ABT on 52 motion-onset visual evoked potential (mVEP) datasets from 26 healthy subjects and compared the classification accuracy of support vector machine (SVM), spatiotemporal beamformer (stBF) and stepwise linear discriminant analysis (SWLDA) when trained on individual subjects and on a population thereof. Main results. When using phase- and combined phase/magnitude information extracted by ABT, we show significant improvements in accuracy of population-trained classifiers applied to individual users (p < 0.001). We also show that 450 epochs are needed for a correct functioning of ABT, which corresponds to 2 min of paradigm stimulation. Significance. We have shown that ABT can be used to create population-trained mVEP classifiers using a limited number of epochs. We expect this to pertain to other ERPs or synchronous stimulation paradigms, allowing for a more effective, population-based training of visual BCIs. Finally, as ABT renders recordings across subjects more structurally invariant, it could be used for transfer learning purposes in view of plug-and-play BCI applications.
A framework for quantifying the effects of transcranial magnetic stimulation on motor recovery from hemiparesis: corticomuscular network
Authors: Tan Gansheng , Wang Jixian , Liu Jinbiao , Sheng Yixuan , Xie Qing , Liu Honghai 
Published: April 2022

Abstract

Objective. Transcranial magnetic stimulation (TMS) is an experimental therapy for promoting motor recovery from hemiparesis. At present, hemiparesis patients’ responses to TMS are variable. To maximize its therapeutic potential, we need an approach that relates the electrophysiology of motor recovery and TMS. To this end, we propose corticomuscular network (CMN) representing the holistic motor system, including the cortico-cortical pathway, corticospinal tract, and muscle co-activation. Approach. CMN is made up of coherence between pairs of electrode signals and spatial locations of the electrodes. We associated coherence and graph features of CMN with Fugl-Meyer Assessment (FMA) for the upper extremity. Besides, we compared CMN between 8 patients with hemiparesis and 6 healthy controls and contrasted CMN of patients before and after a 1 Hz TMS. Main results. Corticomuscular coherence (CMC) correlated positively with FMA. The regression model between FMA and CMC between five pairs of channels had 0.99 adjusted and a p-value less than 0.01. Compared to healthy controls, CMN of patients tended to be a small-world network and was more interconnected with higher CMC. CMC between cortex and triceps brachii long head was higher in patients. 15 min 1 Hz TMS protocol induced coherence changes beyond the stimulation side and had a limited impact on CMN parameters that are related to motor recovery. Significance. CMN is a potential clinical approach to quantify rehabilitating progress. It also sheds light on the desirable electrophysiological effects of TMS based on which rehabilitating strategies can be optimized.
Propulsion optimization of a jellyfish-inspired robot based on a nonintrusive reduced-order model with proper orthogonal decomposition
Authors: Ying Zixiang , Zhang Haozhi , Wang Linxiang , Melnik Roderick 
Published: April 2022

Abstract
In this research, the propulsion of the proposed jellyfish-inspired mantle undulated propulsion robot (MUPRo) is optimized. To reliably predict the hydrodynamic forces acting on the robot, the proposed nonintrusive reduced-order model (NIROM) based on proper orthogonal decomposition (POD) additionally considers the POD basis that makes an important contribution to the features on the specified boundary. The proposed model establishes a mapping between the parameter-driven motion of the mantle and the evolution of the fluid characteristics around the swimmer. Moreover, to predict new cases where the input needs to be updated, the input of the proposed model is taken from the kinematics of the robot rather than extracted from full-order high-fidelity models. In this paper, it takes approximately 950 s to perform a simulation using the full-order high-fidelity model. However, the computational cost for one prediction with the proposed POD-NIROM is around 0.54 s, of which about 0.2 s is contributed by preprocessing. Compared with the NIROM based on the classic POD method, the proposed POD-NIROM can effectively update the input and reasonably predict the characteristics on the boundary. The analysis of the hydrodynamic performance of the MUPRo pinpoints that, over a certain period and with a certain undulation amplitude, the hydrodynamic force generated by the swinging-like mantle motion (k < 0.5) is greater, outperforming Aequorea victoria in startup acceleration. It is demonstrated that considering a certain power loss and a certain tail beat amplitude, the wave-like mantle motion (k > 0.5) can produce greater propulsion, which means higher propulsion efficiency.
Marked non-compliance with deforestation embargoes in the Brazilian Amazon
Authors: Silva Verissimo César Sousa da , Vieira Ima Celia Guimaraes , Galbraith David , Potapov Peter , Rivero Sérgio Luiz de Medeiros , Lima Aline Maria Meiguins de , Pimentel Marcia Aparecida da Silva , Adami Marcos 
Published: April 2022

Abstract
Advances in monitoring capacity and strengthened law enforcement have helped to reduce deforestation in the Brazilian Amazon since the early 2000s. Embargoes imposed on the use of deforested land are important instruments for deterring deforestation and enabling forest recovery. However, the extent to which landowners respect embargoes in the Brazilian Amazon is unknown. In this study, we evaluated the current recovery status of embargoes due to deforestation imposed between 2008 and 2017 to conduct the first large-scale assessment of compliance with embargo regulations. We observed forest recovery in only 13.1% (±1.1%) of embargoed polygons, while agriculture and pasture activities were maintained in 86.9% (±1.8%) of embargoed polygons. Thus, landowners openly continue to disrespect environmental legislation in the majority of embargoed areas. We attribute the marked non-compliance observed to limited monitoring of embargoed areas, as environmental agents seldom return to verify the status of embargoed lands after they have been imposed. Recent advances in remote sensing provide low-cost ways to monitor compliance and should form the basis of concerted efforts to ensure that the law is observed and that those responsible for illegal deforestation do not benefit from it.
The tight-focusing properties of radially polarized symmetrical power-exponent-phase vortex beam
Authors: Chen Kang , Ma Zhiyuan , Zhang Mingming , Dou Jiantai , Hu Youyou 
Published: April 2022

Abstract
In this paper, the radially polarized (RP) new kind of power-exponent-phase vortex (NPEPV) beam, with rotationally symmetrical phase structure, was introduced and the tightly focused properties of the RP NPEPV beam passing through a high numerical aperture objective lens were studied numerically. The results show that with the increase of topological charge l, there are multiple intensity points in the focal region, and the number is consistent with the topological charge. In addition, as the power order n increases, the light intensity gradually concentrates on the central optical axis and the surrounding intensity points gradually disappear, which finally presents a Gaussian intensity distribution with the dark cores gradually move away from the optical axis and disappear. These unique properties will have potential applications in particle trapping and laser fabrication, especially for simultaneous trapping of multiple particles and fabrication of chiral microstructures.
Machine learning assisted insights into the mechanical strength of nanocrystalline graphene oxide
Authors: Xu Yihua , Shi Qiao , Zhou Ziyue , Xu Ke , Lin Yanwen , Li Yang , Zhang Zhisen , Wu Jianyang 
Published: April 2022

Abstract
The mechanical properties of graphene oxides (GOs) are of great importance for their practical applications. Herein, extensive first-principles-based ReaxFF molecular dynamics (MD) simulations predict the wrinkling morphology and mechanical properties of nanocrystalline GOs (NCGOs), with intricate effects of grain size, oxidation, hydroxylation, epoxidation, grain boundary (GB) hydroxylation, GB epoxidation, GB oxidation being considered. NCGOs show brittle failures initiating at GBs, obeying the weakest link principle. By training the MD data, four machine learning models are developed with capability in estimating the tensile strength of NCGOs, with sorting as eXtreme Gradient Boosting (XGboost) > multilayer perceptron > gradient boosting decision tree > random forest. In the XGboot model, it is revealed that the strength of NCGOs is greatly dictated by oxidation and grain size, and the hydroxyl group plays more critical role in the strength of NCGOs than the epoxy group. These results uncover the pivotal roles of structural signatures in the mechanical strength of NCGOs, and provide critical guidance for mechanical designs of chemically-functionalized nanostructures.
Comparison of interfaces, band alignments, and tunneling currents between crystalline and amorphous silica in Si/SiO2/Si structures
Authors: Ko Eunjung , Choi Jung-Hae 
Published: April 2022

Abstract
Recently, to improve the performance of an integrated metal-oxide-semiconductor (MOS) device, an attempt has been made in the industry to replace the amorphous oxide with a crystalline oxide. However, various characteristics caused by the difference between amorphous and crystalline oxide in the MOS structure have not been systematically investigated. Therefore, we demonstrate the difference in atomic interface structures, electronic structures, and tunneling properties concerning varied oxide phases in a representative system, Si/SiO2/Si structures, with sub-3 nm-thick silica from first-principles. We investigate two oxide phases of amorphous (a-) and crystalline (c-) SiO2 with and without H passivation at the interface. Si/a-SiO2 exhibits a smooth interface layer, whereas Si/c-SiO2 exhibits an abrupt interface layer, resulting in the thicker interface layer of Si/a-SiO2 than Si/c-SiO2. Thus for a given total silica thickness, the adequate tunneling-blocking thickness, where all the Si atoms form four Si–O bonds, is thinner in a-SiO2 than c-SiO2, originating more tunneling current through a-SiO2 than c-SiO2. However, the effects of dangling bonds at Si/c-SiO2 rather than Si/a-SiO2 on tunneling currents are crucial, particularly in valence bands. Furthermore, when the dangling bonds are excluded by H atoms at Si/c-SiO2, the tunneling current dramatically reduces, whereas the H-passivation effect on the tunneling blocking at Si/a-SiO2 is insignificant. Our study contributes systematic knowledge regarding oxide phases and interfaces to promote for high performance of MOS devices.
Quantification of Ephedrine Substances in Human Urine by Ultra-Performance Liquid Chromatography–Tandem Mass Spectrometry
Authors: Wang Yunfei , Yan Kuan , Wang Zhanliang , He Genye , Chang Wei 
Published: April 2022

Abstract
An accurate quantitative method for four prohibited ephedrine substances in human urine has been established, based on ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS). The quantitative bias caused by pretreatment operations and matrix effects was reduced by the dilute and shoot pretreatment method. The good separation of isomers was achieved with the advantages of the UPLC instrument and Agilent Poroshell 120 EC-C8 UPLC column. Stable quantitative ions were selected during the analysis with MS/MS. The result of the method validation experiment showed an excellent linearity between 50% and 200% threshold concentration with a correlation coefficient (r2) greater than 0.999. The coefficient of variation at the limit of quantification and threshold was &lt;20% and 10%, respectively. The uncertainty was below the maximum uncertainty specified in the technical document of the World Anti-Doping Agency (WADA). The analytical result using this method has passed the WADA-external quality assessment scheme. The anti-doping laboratory has applied the method in routine tests and reported adverse analytical finding.